Design and
Evaluation of Gatifloxacin Ocular Films for Sustained
Release
Ajaykumar Patil1*, Raga Basawaraj,
Md. Khaleed Ali, Anandkumar
Joshi, Basawaraj Nanjwade2
1Dept. of
Pharmaceutics, Karnataka College of Pharmacy, Manhalli
Road, Bidar-585403, Karnataka, India.
2Dept. of Pharmaceutics, KLE Deemed University,
Belgaum, Karnataka, India.
ABSTRACT:
Gatifloxacin ocular films were prepared by solvent casting method
using hydroxy propyl methyl
cellulose, methyl cellulose, sodium carboxy methyl
cellulose and gelatin in different concentrations using glycerin as
plasticizer. The physicochemical parameters of the ocular films were evaluated.
The compatibility of the drug in the formulations was confirmed by IR studies. In vitro diffusion studies and mechanism
of drug release was identified. The formulation F4 and F8
shows a maximum cumulative percentage drug release of 96.15 % and 97.34 % at
the end of 12th h respectively. The drug release decreases in all
the formulations as the concentration of polymer increases. The release of drug
from the films has followed first-order kinetics and non-fickian
in nature with diffusion controlled mechanism. The formulation F4 and F8 were subjected to
UV-irradiation and in vivo drug
release studies on rabbits. A high correlation coefficient was found between in vitro and in vivo release rate studies. No significant change in the drug
content and physical features was observed during storage at 30±2°C/65±5% RH
and 40±2°C/75±5% RH for three months. The data demonstrated that hydroxy propyl methyl cellulose
and methyl cellulose in the concentration of 4.5% w/v was suitable for
developing sustained release ocular films of gatifloxacin.
KEYWORDS: Gatifloxacin,
Ocular films, HPMC, Sodium CMC, MC, Gelatin
INTRODUCTION:
Gatifloxacin
is a flouroquinolone derivative which shows a broad spectrum antibacterial
activity, it is used in the treatment of bacterial conjunctivitis. It is
available as 0.3 % w/v eye solution. The drug is administered 1-3 drops 3-4
times daily as eye drop1. Traditional topical ophthalmic
formulations have poor bioavailability because of rapid pre-corneal
elimination, conjunctival absorption, solution drainage by gravity, induced lacrimation
and normal tear turnover. This leads to frequent instillations of concentrated
medication to achieve a therapeutic effect. These observations suggest that
increasing contact time between drug and corneal tissue could both be
beneficial for patient compliance and to improve therapeutic efficacy2.
Present study is undertaken to prepare an ocular film with an aim of increasing
the contact time, achieving controlled release, reducing the frequency of
administration, improving patient compliance and obtaining greater therapeutic
efficacy.
Materials and
methods:
Materials:
Gatifloxacin
was obtained as a gift sample from Hetero Drugs (P) Ltd., Hyderabad. The
polymers HPMC, Sodium CMC, MC and Gelatin were purchased from S. D. Fine
Chemicals (P) Ltd., Boisar. All other chemicals and
solvents used were of analytical reagent grade.
Methods:
Preparation of ocular films:
Method
used for the preparation of ocular film is solvent casting technique3
using purified water as a solvent. Table 1 shows composition of cast film for
each ocular film. Polymers were dissolved in 10 ml of purified water using
magnetic stirrer in a beaker to get desired concentration of the polymer. Gatifloxacin and plasticizer were added to the above
solutions under continuous stirring using magnetic stirrer. After complete
mixing, 10 ml solutions were poured into a clean petridish
(Anumbra®, area of 63.64 cm2 approximately)
placed on a horizontal plane. Water was allowed to evaporate slowly by
inverting a glass funnel on the petridish at room
temperature for 24 h. After complete evaporation of the solvent, cast films
were obtained, from these cast films, ocular films of 8 mm diameter (an area of
0.56 cm2) each containing 0.8 mg of drug were cut with
the help of cork borer and wrapped individually in
aluminum foil and stored till used for evaluation.
TABLE 1: COMPOSITION OF FORMULATIONS
|
Formulations |
Polymers (% w/v) |
|||
|
HPMC |
Methyl Cellulose |
Sodium CMC |
Gelatin |
|
|
F1 |
3.0 |
- |
- |
- |
|
F2 |
3.5 |
- |
- |
- |
|
F3 |
4.0 |
- |
- |
- |
|
F4 |
4.5 |
- |
- |
- |
|
F5 |
- |
3.0 |
- |
- |
|
F6 |
- |
3.5 |
- |
- |
|
F7 |
- |
4.0 |
- |
- |
|
F8 |
- |
4.5 |
- |
- |
|
F9 |
- |
- |
4 |
- |
|
F10 |
- |
- |
5 |
- |
|
F11 |
- |
- |
6 |
- |
|
F12 |
- |
- |
7 |
- |
|
F13 |
- |
- |
- |
3.0 |
|
F14 |
- |
- |
- |
3.5 |
|
F15 |
- |
- |
- |
4.0 |
|
F16 |
- |
- |
- |
4.5 |
In
each of the formulations gatifloxacin 1% w/v was
incorporated.
Glycerin
was used as plasticizer 30 % w/w of dry weight of polymer.
Total
volume used was 10 ml.
Evaluation of ocular films:
The
ocular films were evaluated for thickness, weight variation, percentage
moisture absorption, percentage moisture loss and drug
content uniformity. The thickness was measured using a dial caliper (Mitutoyo, Japan) at different points and the mean values
were calculated. Ocular film weights were determined by using electronic
balance.
To check the uniformity of the drug in
the cast film, films were cut at different places in cast films and each film
was placed in 10 ml of water to extract gatifloxacin,
the resulting solution was filtered and further dilution was made with water
and the absorbance at 287 nm was measured spectrophotometrically4.
The concentration of the drug was determined from the standard curve. Same
procedure was adopted for other formulations of cast films in triplicates and
mean drug content and standard deviation were calculated.
Percentage moisture absorption5:
The
percentage moisture absorption test was carried out to check physical stability
or integrity of the ocular films. Ocular films were weighed and placed in a dessicator containing 100 ml of saturated solution of
aluminium chloride and 79.5 % humidity was maintained. After three days, the
ocular films were taken out and reweighed; the percentage moisture absorption
was calculated.
Percentage moisture loss5:
The
percentage moisture loss was carried out to check integrity of the film at dry
condition. Ocular films were weighed and kept in a dessicator
containing anhydrous calcium chloride. After three days, the ocular films were
taken out and reweighed; the percentage moisture loss was calculated.
In
vitro diffusion studies6:
Semi
permeable membrane obtained from Sigma Chemicals Co. having a molecular weight
cut off 12,000 Daltons was used for this study. This membrane was tied to one
end of the open cylinder, which acts as donor compartment. The ocular film was
placed inside the compartment. The semi permeable membrane acts as corneal
epithelium. Then the open cylinder was placed over a beaker containing 50 ml of
phosphate buffer pH 7.4 which acts as receptor compartment. This was
continuously stirred (50 rpm) using a magnetic stirrer. The temperature was
maintained at 37 + 1°C. 1ml of the sample solution was withdrawn at
hourly intervals from the receptor compartment and the same quantity was
replaced with phosphate buffer pH 7.4. The cumulative percentage of drug
released was determined using Elico SL 159 UV-VIS
Spectrophotometer at 287 nm. The experiment was carried out in triplicate and
average values were reported.
Drug excipient
interaction studies:
The
stability of the drug in the formulation was confirmed by IR spectral analysis.
IR spectra of pure drug and formulations were determined using Simadzu FTIR-8400S Spectrophotometer by KBr
Disc method.
Accelerated Stability Studies:
The
optimized formulations in its final pack were stored at 30±20C/65±5%
RH and 40±20C/75±5% RH for 3 months in Stability chamber (Thermolab). The samples were withdrawn at every 10 day time
intervals and analyzed for physical parameters and drug content.
In vivo studies7:
The
ocular inserts were sterilized using U.V. radiation for 10 minutes at 25 cm
height on both sides before in vivo
study. Male rabbits (New Zealand), 10-12 weeks old weighing 1-2 kg were chosen in the present study with prior approval of
Institutional Animal Ethics Committee.
TABLE 2: PHYSICO-CHEMICAL EVALUATION OF
OCULAR FILMS*
|
Formulations |
Weight in (mg) ± SD |
Thickness in (mm) ± SD |
Drug content (mg) ± SD |
Per cent Moisture Absorption ± SD |
Per cent Moisture Loss ± SD |
|
F1 |
3.21
± 0.82 |
0.086
± 0.005 |
0.789
± 0.012 |
4.34
± 0.31 |
7.79
± 0.31 |
|
F2 |
3.69
± 0.51 |
0.087
± 0.005 |
0.788 ± 0.005 |
4.56
±0.43 |
7.94
± 0.12 |
|
F3 |
4.05
± 0.41 |
0.087
± 0.002 |
0.784
± 0.027 |
5.61
± 0.25 |
8.35
± 0.34 |
|
F4 |
4.43
± 0.47 |
0.087
± 0.006 |
0.790
± 0.029 |
5.81
± 0.33 |
8.75
± 0.86 |
|
F5 |
3.26
± 0.55 |
0.086
± 0.002 |
0.787
± 0.007 |
5.74
± 0.19 |
8.45
± 0.32 |
|
F6 |
3.61
± 0.75 |
0.088
± 0.002 |
0.788
± 0.017 |
6.32
± 0.38 |
9.12
± 0.46 |
|
F7 |
4.08
± 0.67 |
0.087
± 0.001 |
0.790
± 0.039 |
6.81
± 0.72 |
9.63
± 0.38 |
|
F8 |
4.45
± 0.47 |
0.086
± 0.002 |
0.784
± 0.015 |
7.22
± 0.69 |
10.75
± 0.83 |
|
F9 |
4.07
± 0.85 |
0.085
± 0.005 |
0.784
± 0.008 |
6.91
± 0.15 |
9.71
± 0.23 |
|
F10 |
4.81
± 0.65 |
0.086
± 0.003 |
0.790
± 0.025 |
7.34
± 0.31 |
11.23
± 0.35 |
|
F11 |
5.62
± 0.88 |
0.084
± 0.002 |
0.787
± 0.010 |
7.81
± 0.67 |
11.81
± 0.84 |
|
F12 |
6.46
± 0.72 |
0.086
± 0.005 |
0.789
± 0.013 |
8.35
± 0.81 |
12.23
± 0.46 |
|
F13 |
3.23
± 0.65 |
0.136
± 0.005 |
0.789
± 0.005 |
8.44
± 0.12 |
12.10
± 0.24 |
|
F14 |
3.61
± 0.63 |
0.143
± 0.005 |
0.790
± 0.013 |
8.64
± 0.15 |
12.83
± 0.81 |
|
F15 |
4.08
± 0.65 |
0.154
± 0.006 |
0.785
± 0.025 |
10.65
± 0.21 |
13.10
± 0.36 |
|
F16 |
4.45
± 0.75 |
0.167
± 0.001 |
0.790
± 0.027 |
11.21
± 0.23 |
14.15
± 0.43 |
*Each
reading is an average of three determinations, SD = Standard Deviation.
They
were kept three per cage with husk bedding and were fed with standard diet and
water as much as required. A dark light cycle of 12 h was maintained. The
ocular films were placed into the lower conjuctival
cul-de-sac of rabbits into five eyes (after five minutes of sterilization
process), each one eye of five rabbits is served as
control. Ocular inserts were removed
carefully at 1, 3, 6, 9 and 12 h and analyzed for residual drug content. The
drug remaining was subtracted from the initial drug content of inserts; which
gave the amount of drug released in the rabbit eye.
RESULTS AND
DISCUSSION:
The
physiochemical evaluation data presented in Table 2 indicating thickness of the
ocular films varies from 0.084±0.002 to 0.167±0.001 mm. The formulations did
not produce any irritation when placed in the cul de
sac, since they were not thick enough to produce irritation. The weight of
ocular films varies from 3.21±0.82 to 6.46±0.72 mg. All the formulations found
to contain almost uniform quantity of drug as per content uniformity studies
indicating reproducibility of the technique. IR spectra
analytical reports shown in fig 1 indicating that there was no interaction
between drug and excipients used.
Figure 1: FTIR Spectra of Gatifloxacin (A), Gatifloxacin + Hydroxy propyl methyl cellulose
(B), Gatifloxacin + Methyl
cellulose (C), Gatifloxacin + Sodium CMC (D) and Gatifloxacin + Gelatin (E)
The
percentage moisture absorption results are shown in Table 2. Formulation F16
showed the maximum percent moisture absorption of 11.21 and formulation F1
shown the minimum percent moisture absorption of 4.34. All the polymers are
hydrophilic in nature and they have tendency to absorb moisture. From the
results it can be concluded that, the formulation containing gelatin shown
maximum moisture absorption followed by sodium CMC, MC and HPMC. At humid
conditions there was more moisture absorption but there was no change in the
integrity; which was observed by its physical appearance.
The
percentage moisture loss results are shown in Table 2. Formulation F16
showed the maximum percent moisture loss of 14.15 and formulation F1
shown the minimum percent moisture loss of 7.79. It was observed that when the
formulations were kept at very dry condition the maximum moisture loss has been
occurred.
The
cumulative percentage drug release of all the formulations are shown in Table
3. The ocular films prepared with HPMC released the drug completely in 10-12 h.
The formulation with MC showed complete release within 8-12 h. The formulation
with Na CMC as the polymer showed complete release of drug within 8 to 11 h.
The formulation with gelatin as the polymer showed complete release of drug
within 2-3 h. As the concentration of polymer in the formulation increases the
drug release decreases. The order of retardation of drug release is HPMC
followed by MC, Sodium CMC and gelatin. The release of drug from the films has
followed first-order kinetics and non-fickian in
nature with diffusion controlled mechanism.
Among
all the formulations, the best formulations were F4 containing HPMC
4.5 % and F8 containing MC 4.5 % since it showed retarded release of
drug up to 12 h. The formulations F4 and F8 were
subjected to stability studies and in
vivo studies.
TABLE 3:
DATA SHOWING In vitro and in vivo CUMULATIVE percentAGE drug
released
|
Formulations |
In
vitro Cumulative Per
cent Drug Released |
||||
|
1st h |
3rd h |
6th h |
9th h |
12th h |
|
|
F1 |
34.55 |
61.00 |
76.57 |
91.51 |
- |
|
F2 |
30.50 |
56.20 |
74.17 |
88.34 |
- |
|
F3 |
28.10 |
50.88 |
67.46 |
85.28 |
- |
|
F4 |
25.06 |
42.02 |
61.13 |
79.08 |
96.15 |
|
F5 |
36.58 |
65.43 |
84.79 |
- |
- |
|
F6 |
32.78 |
58.60 |
82.39 |
97.79 |
- |
|
F7 |
30.63 |
54.04 |
74.80 |
91.38 |
- |
|
F8 |
29.87 |
50.75 |
68.85 |
90.49 |
97.34 |
|
F9 |
42.15 |
56.19 |
82.77 |
93.32 |
- |
|
F10 |
38.60 |
60.37 |
79.99 |
96.31 |
- |
|
F11 |
36.20 |
52.78 |
77.59 |
93.14 |
- |
|
F12 |
30.88 |
48.47 |
73.28 |
92.27 |
- |
|
F13 |
77.71 |
- |
- |
- |
- |
|
F14 |
73.91 |
- |
- |
- |
- |
|
F15 |
65.81 |
- |
- |
- |
- |
|
F16 |
61.00 |
97.69 |
- |
- |
- |
|
|
In
vivo Cumulative Per cent Drug Released |
||||
|
F4 |
2.56 |
19.32 |
38.12 |
56.67 |
65.32 |
|
F8 |
6.46 |
28.45 |
45.61 |
67.24 |
74.25 |
In vivo drug release for formulations F4 and F8 through conjunctival cul-de-sac of rabbits was 65.32 % and 74.25 %
at the end of 12 h respectively. The release pattern followed first order
kinetics. In vitro and in vivo correlation was carried out for
the therapeutic efficacy of the formulation. The correlation coefficient of
formulations F4 and F8 shown in fig 2 were found to be
0.9898 and 0.9998 respectively, indicating that the correlation was strong and
positive. There was no drag out of circular ocular films at the time of
experiment, which suggests that the dimension of the ocular film (8 mm
diameter) were suitable for ocular use. Rabbits subjected for in vivo study did not show any signs of
irritation, inflammation and abnormal discharge that confirmed the safety of
the polymers used in the formulation.
Figure 2: In vitro-In vivo correlation for the release of Gatifloxacin
from F4 and F8 showing coefficient values of 0.9898 and
0.9998 respectively.
From
the results of accelerated stability studies it was found that the formulations
were stable and the drug content was found to be within limits.
CONCLUSION:
From
the results it can be concluded that formulations F4 and F8
has achieved the objective of increased contact time, decreased frequency of
administration, prolonged release.
ACKNOWLEDGEMENTS:
The
authors are thankful to the Principal, Karnataka College of Pharmacy, Bidar, for providing the necessary facilities.
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Received
on 23.03.2010
Accepted on 13.05.2010
© A&V Publication all right reserved
Research Journal of Pharmaceutical
Dosage Forms and Technology.
2(4): July-August 2010, 277-280